Building Blocks of Life
Cell Structures
Cells are made of many organelles, each serving a different function. Each organelle serves a different purpose and function and helps maintain balance throughout the cell.The most important organelles are listed as:
Plasma Membrane Transport
Each cell has an outer plasma membrane responsible for dealing with the exchange of materials outside the cell. Here is a great summary:
In simple diffusion, lipid soluble molecules pass between the phospholipids to enter or leave the cell, moving from areas of high concentration to areas of low concentration ;down their concentration gradient. An example: Oxygen and carbon dioxide and most lipids enter and leave cells by simple diffusion.
Osmosis is a type of simple diffusion in which water molecules diffuse through a selectively permeable membrane from areas of high water concentration to areas of lower water concentration.
Hypertonic and hypotonic. A hypertonic solution contains more solutes as well as less water than a hypotonic solution.. During osmosis, water moves from the hypotonic solution to the hypertonic solution
In facilitated diffusion, substances move into or out of cells down their concentration gradient through protein channels in the cell membrane.
Active Transport- moving substances across membranes against their concentration gradient (from areas of low concentration to areas of high concentration) using energy from the breakdown of ATP.
Endocytosis - large molecules to enter a cell by a process called , where a small piece of the cell membrane wraps around the particle and is brought into the cell.
Exocytosis- the process to allow exiting of large molecules to pass through the cell membrane
In simple diffusion, lipid soluble molecules pass between the phospholipids to enter or leave the cell, moving from areas of high concentration to areas of low concentration ;down their concentration gradient. An example: Oxygen and carbon dioxide and most lipids enter and leave cells by simple diffusion.
Osmosis is a type of simple diffusion in which water molecules diffuse through a selectively permeable membrane from areas of high water concentration to areas of lower water concentration.
Hypertonic and hypotonic. A hypertonic solution contains more solutes as well as less water than a hypotonic solution.. During osmosis, water moves from the hypotonic solution to the hypertonic solution
In facilitated diffusion, substances move into or out of cells down their concentration gradient through protein channels in the cell membrane.
Active Transport- moving substances across membranes against their concentration gradient (from areas of low concentration to areas of high concentration) using energy from the breakdown of ATP.
Endocytosis - large molecules to enter a cell by a process called , where a small piece of the cell membrane wraps around the particle and is brought into the cell.
Exocytosis- the process to allow exiting of large molecules to pass through the cell membrane
A lab done to further explain cells was the Cheers for Spheres Lab. In the lab we learned multiple concepts of cell size. From observing as size increases what happens to color we were able to learn the main concepts. The purpose for the lab was to determine how the size of a sphere, measured by its radius, affects the surface area to volume ratio and to discover the trends regarding this relationship. As a sphere grows larger, the surface area to volume ratio decreases or slowly balances, which hypothetically would make a cell less efficient due to the lack of channels in the membrane to allow molecules to pass in and out. The bigger the radius, the smaller the surface area to volume ratio is. For example, a basketball has the radius of 11.62 cm and the smallest surface area to volume ratio of 0.26 cm. Although the BBs have a small radius, 0.21 cm, they have a large surface area to volume ratio of 14.23 cm. Due to the increase in size, the volume grows larger which means there are more matter or molecules compacted within the sphere or a cell. However, the surface area of the sphere increases at a slower rate since it takes less surface area expansion to accommodate added volume. To allow for proper function of such rapid diffusion, there needs to be an abundance in the channels in the membrane which means a large amount of surface area. When there’s not enough open pathways to allow for transfer, essential molecules such as sugar, protein, and water are being blocked outside or inside the cell which causes a major defect in the purpose of a cell. Therefore the ratio between surface area and volume has to be large to make for full and efficient use of cell functions in a body.